This invention is an improvement of the switch actuator shown in my U.S. Pat. No. 4,094,247 granted June 13, 1978 and is hereby incorporated by reference. That invention represented a significant advance in the art for means to safe and arm a missile and to prevent the missile from being prematurely or inadvertently detonated by an extraneous signal. It utilized a dual coded optical input which was transduced by a photosensitive cell into an electrical signal which was amplified and then converted by a solenoid means into a pneumatic signal of the same coded format. The pneumatic coded signals were decoded by a rotary decoding plate valve which was geared to a pneumatic prime mover. The prime mover was mechanically connected through a geneva drive mechanism to a rotary drive switch. The prime mover had to receive a plurality of consecutively, properly timed pneumatic pulse signals before the output switching action could be initiated by the device.
The above-mentioned prime mover was a three cylinder pneumatic motor of the piston type. Although satisfactory, it was found that this design needed improvement in sensitivity and response.